Lubrication of steam cylinders



Patented June 23, 1953 T2,'642;722 LUBRICATION or STEAM CYLINDERS Samuel ci'yue :v'mi 'hn, Berkeleflw'Califi, rassignor to .Tide Water Associated Oil Company, "San Francisco, Calif.,-.a corporation of,Delaware .Nninmwin ApplicationMay'25, 1949,

Serial No. 95,377 v e 1 V This invention relates to the "lubrication of steam engines and, specifically, to the lubrication of the cylinders and '-valves ofreciprocating steam" engines which are operated"- with wet orsaturated steam. Aparticular feature of the'irrvention is the'use of'a 'special oil corrib'ination' in a specific manner with many resulting advantages" not hitherto obtained in the art. A specific rum-r the invention includes therecovery of the steam 9 Claims. (01, fill-Gail madeto'recover condensate'zf'rom"engines-operatingonrs'aturated'steam, "as it is generally :preierred treat additional ffreshtboiler water than to put up'with'tlie prioblemsinvolved in breaking the oil-water emulsions. Furthermore, high viscosity oils' are relatively more expensive, more difficultflto refine, and :are less available than lower viscosity oils. .In addition, the'added cost the oil while permitting prompt breaking of the emulsion "and liberation of water'when theexhaust steam is condensed and recovered ror "return to the boiler.

Although reciprocating steam, engines are one of the oldest forms of prime movers, the lubrication of theirpistons and-cylinders present many problems'not present in the lubrication of other types of motive power such as steam turbines and internal combustionengines. Particularly, is this true of reciprocating engines operating on satu rated'or wet steam, where moisture tends to condense on the cylinder walls and wash ofith'e oil film which is supplied for'lubrica'tion. Due-to the temperatures and pressures encountered,

along with the"moisture'lubrication of theserengines has, to date, been primarily acompromise between various factors. For example, it is generally recognized that high viscosity oils (i. .e, a

viscosity above 100 S. U. at ZIO R) 'areneeded to furnishsadequate lubrication! at the temperatures involved, but, on the other .hand, 4 such high viscosity oils. generall-yhave high. carbon residues and more readily decompose causingcarb'onaceous deposits on the piston ringsend .pi'stons.

When the engines are operated cold weather however, these emulsifiers are extremely trouble-- some-when it is attempted ftoxrecover the exhaust steam for boiler'water feed; In-tfact, for this reason, inmost modern practice. zno-zattemptf-is' of "the emulsifying agentxmay be appreciable.

Due partly to the'enorrnous viscosities acquired during storage at lowtemperatures by steam cylinder'oi'ls (of sui-ta'ble viscosityat engine temperatures) derived from 'naphthene base and other low viscosity-index. 'crudes; Pennsylvania and other high v-iscosity index oils are generally usedib'y the trade in spite of their high cost and relative scarcity.

In accordance with the :present invention "all the above disadvantages-present in the conventional lubrication of reciprocatingsteam engines are either eliminatedor greatly alleviated, while. attaining a degree of lubrication equalto, and generally exceeding, present practice. To this end I have found that, when a light refined oil of about .55 to S. U. viscosity at 210-F.and containing about 0.015% of an acid alkyl phosphate is :commingled with the steam supplied to a steam engine, under the operating conditions occurring in the cylinder and valve chamber the oil will immediately emulsify with moisture present and, upon being deposited on the engine surfaces, will adequately wet and lubricate the working sur-'- ,faces. The emulsion, however, contrary to those usually encountered in wet steam cylinder lubrication,1is of a rathertransient nature maintained primarily by the temperatures, pressures, and agitation occurring within the engine, and, though adequate to provide excellent wetting of theiengine partswith the oil, the emulsion readily breaks upon being exhausted from the: engine and beingipermitted to remain for a short time in a relatively quiescent ,zone.

tion, the base oil used should beawell refined oilof'rather critical,yiscosity limits. vI prefer to use an oil .of about-55 to 65 S. U.L viscosity at 210 FL,.althougharan'geof 50 .to S. Uoat 210 F.

' may beused. Lower viscositytoilsare proneto Accordingly, by. 'con- 7 densing thelsteam and permitting the condensate. to settlefora short-period, the'cond'ensed water give inadequate lubrication, while higher viscosity oils do not readily demulsify and separate from the condensate. The base oil should be stable, of low carbon forming tendencies and, before the addition of the alkyl phosphate, should not have emulsifying tendencies. Accordingly the degree of refinement is important to the extent that reactive bodies and non-hydrocarbons (such as olefins, phenols, naphthenic acids, and the like) should be substantially absent. Many refining processes are known to the art which will remove unstable constituents, and any of these are suitable for the preparation of the base oil. Sulfuric acid refining and solvent refining are examples of suitable processes to produce a refined hydrocarbon oil within the requirements of the invention. Since one of the advantages of the invention is the elimination of carbon deposits in the engine, an oil of low carbon-residue is greatly to be preferred.

The percentage of acid alkyl phosphate in the oil is critical. Too small an amount will result in unsatisfactory emulsification with water within the engine, while too much will prevent proper separation of oil from the condensed exhaust steam. A weight percentage of 0.007 to 0.03 may be used satisfactorily, though 0.015% by weight is preferred. The acid alkyl phosphates suitable for use in the invention are the mono or di alkyl phosphates having from 8 to 18 carbon atoms in the alkyl group. They may be mixtures of such alkyl phosphates, and a convenient mixture, now on the market under the trade name of Ortholeum 162, is understood to be approximately a 50:50 mixture of mono and di alkyl phosphates derived from C3 to C12 alcohols from coconut fatty acids.

The amount of oil to be commingled with the steam and the method of its injection may vary considerably according to individual requirements. By far the best way to inject the oil is mild steel rings was equipped with new rings and piston and placed in operation on 150# gage saturated steam containing some condensed water. An oil having the following characteristics was injected into the steam line by a positive-injection type atomizer at the rate of one pint per 10,000 double strokes:

Type of crude Mixed base Refinement Furfural extraction Viscosity at 210 F. S. U. 61 Viscosity index Pour point F.) Carbon residue (per cent) 0.04 Acidity (ASTM method D974-48T) 0.03 Color (ASTM method D155-45T) 2 Emulsion number (ASTM method D157-36) below 600 To the above oil was added, before injection, 0.015% by weight of Ortholeum 162. The exhaust steam was passed through a cooling line sufficient to condense the steam and the condensate wasrun to a separation vessel. During a residence time in the vessel of about 30 minutes the oil separated from the condensate. After separation water was removed from the bottom of the vessel and returned to theboiler. This water was clean and contained but a trace of oil in suspension. The separated oil was removed at intervals, and inspected and found to be clean enough for re-use after filtration of suspended foreign matter. After three months operation and, again, after nine months operation the engine was disassembled and checked for condition and wear. Results are set forth in the following table, together with results expected from conventional operation using a Pennsylvania bright stock of 100 S. U. viscosity at 210 F. plus 10% acidless tallow oil for lubrication.

Time Start 3 Months 9 Months Conventional Strokes (double) 3,000,000... 9,000,000... 9,000,000. Oil used (gallons) 40 125 200,

Liner I. D. (inches) Condition of rings Ditty. Condition of ring lands. Gummed Packing of piston rod Recovery of condensate I Impractical.

1 Replacement needed. 1 Usual to replace packing about every three months.

by means of the conventional atmoizer placed in the steam line just ahead of the valve chamber. The atomizer should be set to inject from about 1 to 5 pints per 24 hours for engines up to 12 inches in diameter, and proportionately larger amounts for larger engines. For continuous high speed operation (300 R. P. M.) the quantity required may be as little as one pint per 100,000 pounds of steam supplied to the engine. While for slow and intermittent operation somewhat more oil is required, the quantity need not be greater, in most instances than one pint per 2,000 pounds of steam. I

The following example is illustrative of the practice of the invention and its benefits.

An 8" bore steam pump of the slide valve type equipped with cast iron piston and cylinder and 75 210 F. and containing from about 0.007% to.

The above table illustrates the many advantages to be gained by the practice of the invention over conventional practice in the lubrication of steam cylinders, resulting in better lubrication while providing a means whereby steam condensate may be recovered.

In the appended claims the term alkyl acid phosphate is intended to mean either a single alkyl acid phosphate or a mixture of two or more alkyl acid phosphates.

I claim:

1. In the lubrication of the cylinders of steam engines, the improvement which comprises supplying to the cylinder walls of a steam engine operating on saturated steam a refined hydrocarbon oil having a viscosity not over 70 S. U. at

about 0.03% by Weight of alkyl acid phosphate having from 8 to 18 carbon atoms in the alkyl group.

2. In the lubrication of the cylinders of steam engines operating on saturated steam, the improvement which comprises commingling with the steam supplied to such cylinders a refined hydrocarbon oil having a viscosity not over 70 S. U. at 210 F. and containing from about 0.007% to about 0.03% by weight of alkylacid phosphate having from 8 to 18 carbon atoms in the alkyl group.

3. The improvement specified in claim 2 in which the specified oil is injected in the form of a fine mist into the steam immediately before the steam enters the engine and is so furnished at a rate not exceeding one pint per 2,000 pounds of steam.

4. The improvement specified in claim 2 wherein the alkyl acid phosphate is a mixture of mono-alkyl phosphates and di-alkyl phosphates derived from C3 to C12 alcohols obtained from coconut fatty acids.

5. The method of lubricating the cylinders of reciprocating steam engines operating on saturated steam, which comprises spraying into saturated steam supplied to a reciprocating steam engine a refined oil having a viscosity at 210 F. of 50 to 70 S. U., and regulating the character of the emulsion formed by said oil and moisture in the cylinders of said engine under operating conditions by providing as a component of said oil from 0.007% to 0.03% of an emulsifier consisting of alkyl acid phosphate having from 8 to 18 carbon atoms per alkyl group.

6. The method of lubricating the cylinders of reciprocating steam engines operating on saturated steam while recovering exhaust steam for boiler feed water, which comprises spraying into saturated steam supplied to a reciprocating steam engine a refined oil having a viscosity at 210 F.

of to S. U., supplying to said steam as a component of said oil from 0.007% to 0.03% of alkyl acid phosphate having from 8 to 18 carbon atoms per alkyl group whereby said phosphate causes said oil to form a temporary emulsion with moisture in the cylinders of said engine under operating conditions, condensing the exhaust steam. permitting the resulting condensate and oil emulsion to settle, decanting the resulting water layer from the resulting oil layer and introducing said water into a boiler as feed water.

7. The process of claim 6 in which the specified oil is sprayed into the steam at a ratio not exceeding one pint of oil per 2,000 pounds of steam.

8. The process of claim 6 in which the alkyl acid phosphate is a mixture of mono-alkyl phosphates and dialkyl phosphates derived from alcohols obtained from coconut fatty acids.

9. As a new composition adapted for use as a lubricant for cylinders of steam engines, a refined hydrocarbon oil having a Saybolt viscosity between 50 and 70 at 210 F. having dissolved therein from about 0.007% to 0.03% by weight of an alkyl acid phosphate containing an alkyl group of from 8 to 18 carbon atoms.

SAMUEL CLYDE VAUGHN.

References Cited in the file of this patent UNITED STATES PATENTS Burk July 28, 

6. THE METHOD OF LUBRICATING THE CYLINDERS OF RECIPROCATING STEAM ENGINES OPERATIING ON SATURATED STEAM WHILE RECOVERING EXHAUST STEAM FOR BOILER FEED WATER, WHICH COMPRISES SPRAUING INTO SATURATED STEAM SUPPLIED TO A RECIPROCATING STEAM ENGINE REFINED OIL HAVING A VISCOSITY AT 210* F. OF 50 TO 70 S.U., SUPPLYING TO SAID STEAM AS A COMPONENT OF SAID OIL FROM O.007% TO 0.03% OF ALKYL ACID PHOSPHATE HAVING FROM 8 TO 18 CARBON ATOMS PER ALKYL GROUP WHEREBY SAID PHOSPHATE CAUSES SAID OIL TO FORM A TEMPORARY EMULSION WITH MOISTURE IN THE CYLINDERS OF SAID ENGINE UNDER OPERATION CONDITIONS, CONDENSING THE EXHAUST STEAM. PERMITTING THE RESULTING CONDENSATE AND OIL EMULSION TO SETTLE, DECANTING THE RESULTING WATER LAYER FROM THE RESULTING OIL LAYER AND INTRODUCING SAID WATER INTO A BOILER AS FEED WATER. 